What is the recommended management strategy for primary open‑angle glaucoma in adults, including first‑line medication, adjunctive therapy, laser treatment, and surgical options?

Management of Primary Open-Angle Glaucoma

Begin treatment immediately with a prostaglandin analog eye drop (first-line) targeting at least 20-30% IOP reduction from baseline, document optic nerve structure and visual fields before starting therapy, and escalate to laser trabeculoplasty or trabeculectomy if medical therapy fails to prevent progression. 1, 2

First-Line Medical Therapy

Prostaglandin analogs are the preferred initial medication because they provide superior IOP reduction (demonstrated 3.8 mmHg reduction with latanoprost) and significantly reduce visual field deterioration risk (hazard ratio 0.44, P=0.003). 1, 2

Alternative first-line options include:

• Beta-blockers (non-selective agents like timolol) – achieve approximately 20-25% IOP reduction 2
• Alpha-2 adrenergic agonists – useful as monotherapy or adjunctive therapy 3
• Topical carbonic anhydrase inhibitors – effective for additional IOP lowering 3

Critical Medication Contraindications

Avoid non-selective beta-blockers entirely in patients with asthma or COPD because they cause bronchospasm; if a beta-blocker is essential, use cardioselective betaxolol (18% IOP reduction without pulmonary exacerbation). 2

Minimize or discontinue corticosteroids immediately in patients requiring steroid therapy, as corticosteroid use is a major risk factor for glaucoma progression, particularly in those with family history of glaucoma. 4

Target IOP Strategy

Set your initial target at 20-30% below the patient's baseline IOP, then adjust based on disease severity and progression: 1, 2

• Mild glaucoma (optic disc/RNFL abnormalities with normal visual fields): 20-25% reduction 1
• Moderate glaucoma (visual field defects not within 5° of fixation in one hemifield): 25-30% reduction 1, 5
• Severe glaucoma (bilateral field defects or loss within 5° of fixation): ≥30% reduction 1, 5

For high-risk patients—African Americans, Latinos/Hispanics over age 60, or those with documented progression—target more aggressive reductions (≥30%) because these populations have 3-fold higher POAG prevalence and 25% risk at IOP of 30 mmHg. 1, 2

Normal-Tension Glaucoma Exception

Do not withhold IOP-lowering treatment in patients with "normal" office IOP measurements (occurs in nearly 40% of POAG patients), because clinical trials prove IOP reduction still slows progression even when baseline pressures are ≤21 mmHg. 1, 2, 5

Adjunctive Medical Therapy

Add a second medication from a different class when monotherapy fails to achieve target IOP or prevent progression: 2, 3

• Prostaglandin analog + beta-blocker
• Prostaglandin analog + alpha-2 agonist
• Prostaglandin analog + topical carbonic anhydrase inhibitor

Combination drops improve adherence compared to multiple separate bottles, addressing the critical problem that up to 45% of patients take less than 75% of prescribed doses. 2

Laser Trabeculoplasty

Proceed to selective laser trabeculoplasty (SLT) or argon laser trabeculoplasty (ALT) when medical therapy inadequately controls IOP or the patient cannot tolerate medications. 1, 2

• Achieves 30-38% IOP reduction 1, 2
• Particularly effective in African descent patients (30% IOP reduction), who demonstrate better long-term outcomes with laser-first approach compared to Caucasians 1, 6
• Can be repeated if initial effect wanes 1

Incisional Surgery

Reserve trabeculectomy or tube-shunt surgery for patients failing both medical and laser therapy, or those with advanced disease at presentation: 1, 2

• Trabeculectomy provides the greatest IOP reduction (46-60%) but carries higher surgical risks including cataract formation, hypotony, and infection 1, 2
• Surgical outcomes vary by race: Caucasian patients achieve better long-term results with trabeculectomy-first (48% IOP reduction at 4+ years), while African descent patients do better with laser trabeculoplasty initially 1, 6
• African descent is a risk factor for trabeculectomy failure, requiring consideration of alternative approaches like Ex-Press shunts, though evidence remains limited 6

Mandatory Baseline Documentation

Before initiating any therapy, obtain: 1, 2, 5

• Gonioscopy to confirm open angles and exclude secondary causes (pigment dispersion, pseudoexfoliation, uveitis, trauma, steroid-induced) 1, 5
• Central corneal thickness measurement because thin corneas are a risk factor and affect IOP reading accuracy 1, 5
• Stereoscopic optic nerve examination documenting cup-to-disc ratio, rim thinning (especially superior/inferior poles per ISNT rule), disc hemorrhages, RNFL defects, and parapapillary atrophy 1, 5
• OCT imaging of optic nerve head, RNFL, and macula for quantitative baseline 1, 5
• Standard automated perimetry (24-2 or 30-2 testing) to establish baseline visual field status 1, 5
• Add 10-2 visual field testing to detect early central damage missed on 24-2/30-2 grids 5

Monitoring Protocol

Repeat visual field testing and optic nerve imaging at regular intervals (every 3-6 months initially, then annually if stable) to detect progression: 1, 5

• Lower the target IOP immediately if any progression occurs in visual fields, optic nerve structure, or RNFL/macular imaging 1, 5
• Disc hemorrhages on follow-up signal focal progression requiring closer surveillance and more aggressive IOP targets 1, 5
• Adjust visual field testing strategy for advanced disease (use 10-2 grids, vary stimulus size) to accurately monitor remaining central vision 1

Critical Pitfalls to Avoid

Never "observe" a patient with documented optic nerve damage and visual field loss—this defines glaucoma requiring immediate treatment, not observation. 5

Do not rely on a single IOP measurement or use 21 mmHg as a diagnostic cutoff because 13-71% of patients with IOP >21 mmHg do not have glaucoma, while 40% of POAG patients have normal office pressures. 1, 2

Recognize that glaucoma is bilateral but asymmetric—monitor both eyes with equal vigilance even when one appears unaffected. 1, 5

Address medication adherence proactively through patient education, simplified regimens, and regular reinforcement, as non-adherence is the primary cause of treatment failure. 2, 7

Screen high-risk patients aggressively: African Americans >40 years, Caucasians >65 years, first-degree relatives of glaucoma patients (9.2-fold increased odds), diabetics, and those with thin corneas. 1, 7

Prognosis

Early diagnosis and adequate IOP control generally prevent visual disability, but glaucoma remains a chronic, progressive disease requiring lifelong monitoring to preserve visual function. 1, 5